Fuel control system for turbo power plants



Oct. 9, 1951 N. c. PRICE FUEL coNTRoL sYs'rEu FOR TURBO POWER PLANTS 2Sheets-Sheet l Original Filed March 6, 1942 .ntv

n te Nv INVENTOR NATHAN C. PRlcE BY Agent Oct. 9, 1951 N. c. PRICE2,570,591

FUEL CONTROL SYSTEM FOR TURBO POWER PLANTS y Original Filed March 6,1942 2 Sheets-Sheet 2 l Ef 27 39 38 lm'rlou l2 STARTER 2 PoweR Y Fusi.Pumr7 SUP. FUEL lNvENToR. NATHAN C. PRICE Agent Patented Oct. 9, 1951FUEL CONTROL SYSTEM FOB TURBO POWER PLANTS Nathan C. Price, Los Angeles,Calif., assignor to Lockheed Aircraft Corporation, Burbank, Calif.

Application September 8, 1945, Serial No. 615,167,

which 433,599, March 6,

17 Claims.

This invention relates to internal combustion powerplants and relatesmore particularly to fuel control systems for internal combustionturbine powerplants. The mechanism or system of the present invention isintended primarily for embodiment in internal combustion turbopowerplants employed to propel aircraft and other high velocityvehicles.

This application is a division of my'co-pending application, Serial No.615,167, filed September 8, 1945, which in turn is a division of myco-pending application Serial No. 433,599, filed March 6, 1942, nowPatent No. 2,540,991.

It is a general object of the present invention to provide a practical,eillcient and dependable fuel supply and control system for internal combustion turbine powerplants which system autois a division ofapplication Serial No.

1942, now Patent No. 2,540,991, dated February 6, 1951. Divided and thisapplication April 26, 1947, Serial No. 744,238

(Cl. Gli-35.6)

matically establishes and maintains an eflicient air-fuel mixture in thecombustion chamber or chambers of the powerplant under all conditions ofpowerplant operation.

Another object of the invention is to provide a y fuel control system ofthe character referred to in which the pump driving motor is associatedwith the manually operable throttle control lever, or the equivalent, insuch a manner that the fuel pressure supplied to the fuel distributingsystem is directly related to the fuel quantity requirements at thevarious powerplant speeds. The power input to the pump driving motor iscontrolled or adjusted by the throttle control lever so that the speed`of the pump is directly controlled according to the fuel quantityrequirements. This results in the conservation of power required fordriving the pump and prevents fuel vapor lock due to frictionaloverheating of the fuel lines, etc.

Another object of the invention is to provide a fuel control systemembodying a fuel metering means interposed between the fuel pump and thefuel injection nozzles which metering means automatically operates tometer thev fuel in accordance with the air ow through the combustionzone. The metering means' is responsive to the combined function of therates of flow of air and fuel to the combustion zone and ktends tomaintain a proper eflicient fuel-air ratio for each power controlsetting.

A further object of the invention is to provide a fuel control system ofthe class referred to which incorporates fuel metering means for theprimary combustion zone and the secondary or supplemental combustionzone which function in a sequence relation to meter the fuel to bothzones. The metering means for the fuel supplied to the supplementalcombustion zone is subject to the same regulation as the primary fuelmetering device and the aggregate quantity of fuel supplied to the twocombustion zones does not exceed the optimum fuel burning capacity ofthe plant or subject the powerplant elements to excessive temperatures.

Other objects and features of the invention will become apparent fromthe following detailed description of a typical preferred embodiment,throughout which description reference will be made to the accompanyingdrawings, in which:

Figure 1 is a side elevation of a powerplant in which the fuel controlsystem of the invention is embodied, with a major portion broken awayplant of the class disclosed in my co-pending applications referred toabove. The general st'ucture of the powerplant is briefly described becIuse the fuel controlsystem is intimately related with the severalpowerplant elements and mechanisms. However,.the specific details of thepowerplant are omitted as not being essential to an understanding of theinvention.

The powerplant is adaptedfor use in propelling high speed, high altitudeaircraft and is designed to handle a substantial volumetric air flow.The plant comprises generally first and second stage compressors IU andII, a primary combustion chamber I2, a gas turbine I3, and a secondarycombustion chamber I4. v

The rst stage compressor I0 is of the axial flow type and is equipped atits forward end with a tubular spigot I5 which faces forwardly relativeto the direction of flight of the aircraft so as to receive the rammedair. The compressor I0 includes a tubular housing I 6 and a rotor Ilsupported for rotation in the housing. The rotor impeller blades. Therearor exhaust end of the compressor l0 terminates at a double scrollout-l let housing 20 having a pair of outlet spigots 2l and 22 whichcommunicate with intercoolers 23.

The second stage compressorv I lf-isof vthe multistage radralow vand.comprises'three stages 24. 25 and 26 of centrifugal compressionarranged in series or tandem relation. The rst stage centrifugalcompressor 24 is at the -rear of the scroll housing and has two spigots21 and 28 receiving the first stage compressed air from the intercoolers23. The annular exhaust duct of the compressor 24 directs the compressedair through a liquid fed intercooler 30 which, in turn, delivers the airto the inlet 3| of the second stage of centrifugal compression. Thesecond and third stage centrifugal compressors kand 26 'are directlyconnected in tandem and the air from the final stage compressor passesthrough diffuser vanes 32 to the combustion chamber I2.

The combustion chamber I2' comprises a housing 33 and an annular shroud34 which together define an annular space leading from the exhaust ofthe nal stage compressor 26 to the nozzle ring 35 of the gas turbine I3.The housing 33` and shroud 34 are shaped to have an annular series ofparallel pockets for containing pa.rs of concentric burner tubes 36.'Ihe concentric tubes 36 are spaced apart to leave annular combustionspaces which are substantially Venturi shaped to have somewhat confinedZones. Radial openings |49 pass through the walls of the inner tubes 36at said zones. Fuel injection nozzles 31 extend into the forward ends ofthe innermost burner tubes 36 and are supplied with compressed air andfuel by annular supply manifolds 38 and 39. The nozzles 31 d.scharge thefuel-air mixture laterally through said openings |48 into the abovementioned annular Venturi shaped passages. Electrical resistance glowplugs 48 extend into the Venturi shaped passages of the combustionchamber I2 to ignite the fuel and air mixture.

The gas turbine I3 which is driven by the expanding gases of combustionand air issuing from the combustion chamber I2 includes a housing 4|which extends rearwardly from the combustion chamber. A rotor 42 is xedto a central shaft 43 and rotates within the housing. Impeller bucketsor blades 44 on the rotor 42 operate between rows of stator blades 45 onthe interior of the housing 4|. The nozzle ring 35 discharges the gasesof combustion from the combustion chamber I2 into the expansion zone ofthe turbine to drive the rotor 42.

The secondary combustion chamber I4 is dened by a tubular wall or casing46 which extends rearwardly from the turbine casing` 4I. The casing 46is of rearwardly diminishing diameter and its rear end carries apropulsive jet forming nozzle 41. In accordance with the inventionsupplemental fuel is injected into the secondary combustion chamber I4when additional power is desired. The means for injecting thesupplemental fuel includes a cap 48 on the apex of the turbine rotor andprovided with divergent fuel injecting orices 49. The rotor shaft 43 istubular and conducts the fuel from an elbow fitting 59 to the hollow cap48. The supplemental fuel injected from the orifices 49 burns in theexcess air leaving the turbine I3 to materially increase the thrustoutput of the powerplant. An internal annular baffle 5I of streamlinedcross section is supported in the supplemental combustion chamber tosurround and directly oppose the series of fuel injecting orifices 49.

The turbine I3 drives the compressors I8 and II through the medium ofgear drives or transmissions. A beveled gear 52 is fixed on the forwardend of the rotor shaft 43 and meshes with beveiedpinions sa ywhich' arespuneditoradiai. auxiliary shafts 54.-' The compound radial flow lcompressor' I l-hasashaft 55 and a beveled gear 56' is fixedv on thisshaft to mesh .with the-pinions 53. It will be seemhowv the compressorshaft 55 is driven counter to the turbine rotor 42 by the gearing justdescribed. The compressor shaft 55 in turn drives the rst stagecompressor I8 through the medium of a suitable transmission which mayinclude a beveled gear 51 fixed on the forward end of the shaft to meshwith pinions 58. The pinions 58 are fixed on radial shafts 68 which mayproject from the powerplant housing to drive auxiliaries. The end wallof the first stage rotor I1 carries a beveled gear 6| which is in meshwith the pinions 53 so that the first stage compressor is driven by thegearing.

The fuel control system of the invention includes a fuel valve housing18 containing valves for the primary and secondary fuel injection andcylinder and piston means for operating the same. See Figure 2. A lever68 is positioned below the valve housing 18 and one end of the lever ispivotally connected with a piston rod 8| projecting from the valvehousing 18. A spring 65 is arranged under compression between the otherend of the lever 68 and a relatively stationary abutment 66. A coilspring 82 serves as an elastic connection between an intermediate pointon the lever 68 and a control lever 83. The spring 65 serves as anelastic fulcrum for the lever 68 and allo-ws the angle of the lever tochange without imposing bending forces on the piston rod. The throttlecontrol lever 83 may be located in the flight compartment so as to beconveniently manually operatedv by the pilot or flight engineer. In

case the control station for the pilot or flight engineer is remote fromthe powerplant control auxiliaries, the lever 83 may be actuated throughsuitable linkages or cables not shown. Ihe throttle control lever 83 ispivotally supported at 84 on a suitable portion of the aircraftstructure. i

A second coil spring 85 normally acts under compression between asecondary, fuel valve piston rod 86 and a point on the control lever 83intermediate its fulcrum 84 and the first coil spring 82. The piston rod86 is parallel `with the above mentioned rod 8| and enters the valvehousing 18. The free or outer arm of the throttle lever 83 is adapted tom'ove across a suitably calibrated sector 81. The opposite orfulcrum endof the lever Y83 has `an arm 88 which is adapted to actuate an ignitionand fuel pump switch 89 and then actuate a starter switch 9U when thelever is moved across the sector 81 in the direction indicated by thearrow in Figure 2.

The above mentioned primary and secondary fuel valve piston rods Bland86 pass through suitable stuing boxes to enter the valve housing 18, andthe two rods lare slidably guided in openings in an intermediatepartition or wall 9|. The rods 8| and 86 have gas-tight and liquidtightsliding engagement in the openings. The inner ends of the Arods 8| and86V have needle points 92 and 93 respectively which are adapted to seaton correspondingly beveled outlet valve seats 94 and 95 when in theclosed positions. Outow fuel pipes 96fand 91 extend from the seats 94and 95 to the `powerplant fuel injection systems.

The valve housing 18 has a pair of cylinder bores 98` and 99 and thepiston rods 8| and 86 carry pistons `Illl and I9I which have sliding uidtight fits in the bores. The cylinder bores 5 9| and 99 are formed inthe lower portion of th valve housing and the respective upper and lowerends of the bores are interconnected by ducts |02 and |03. An yairpressure pipe |04 leads from the discharge of the nal stage compressor26 to the upper ends of the interconnected cylinder.

bores. An inlet nipple |05 may extend through the combustion chamberhousing 33 to place the pipe |04 in communication with the high pres-Vfsure air duct leading to the combustion chamber. A vacuum pipe |06leads from the vlower ends of the interconnected cylinder bores 98 and99 to a Venturi section of a burner tube 36. This starting system may beof the class disclosed and claimed in my co-pending application SerialNo.v

615,167,`1ed September 8, 1945. Y In the operation of the apparatus itwill rst be assumed that the throttle lever 83 is moved alongthe sector81 from the stop position to the' position designated ignition. Themovement of the lever 83 causes actuation of the switch 89 to complete alow voltage circuit through the glow is shown at s2 in Figure 1. It willbe seen that the pipes and connections just described operate to providedifferential pressures on the opposite sides of the pistons and |0|.

A pair of cylinder bores |01 and |08 is formed in the upper portion ofthe valve housing 18 above the wall 9|. The above mentioned piston rods8| and 86 extend through the bores |01 and |08 and carry pistons |09 and||0 respectively which have loose sliding ts in their respectivecylinder bores. A duct in the housing'ls interconnects the lower ends ofthe cylinder bores I |01 and |08 and a fuel supply pipe ||2 extends fromthe duct to a fuel feed pump P. The pump `P in turn has its suction orlow pressure side in direct communication with the bottom of a fuelstorage tank T to avoid the possibility primary combustion chamber andthe -pipe 91v carries fuel to the combustion chamber housing i 33 whereit passes to the tubular rotorshaft 43 for ultimate discharge from thesupplemental fuel orifices 49.

The invention includes an actuating and control circuit for the fuelpump P. The pump P is driven by an electric motor M and the inventionincludes a system for varying the electrical input to the motor inaccordance with the throttle setting and the fuel demand of thepowerplant.

A rheostat |I4 is arranged to be actuated by the piston rod 8| and lever68. The rheostat ||4 may have a common support with the fuel valvehousing and includes a pivoted contact arm ||5. The arm ||5 isactuatedby a link ||6 interconnecting the lower end. of the piston rod 8| and acrank secured on the arm H5. Movement of the arm ||5 controls or Variesacircuit completed through the snap switch 89, a battery ill, aconductor ||8,' the 're-v sistance of the rheostat ll4, and a conductor|9 to the motor M. The return of the circuit is by way. of the groundconnections illustrated. It will be seen that the electrical power inputto the fuel pump drive is adapted to' be varied as a function of thethrottle lever setting `and the fuel demands of the power plant. Aparal-p lel circuit is completed through the glow plugsV 40 by theswitch 89 from the battery |I1 through a conductor and back throughthenground connections. The above` mentioned plugs 4'0.'. .At theisametime the circuit to the fuel pump motor'Misjalso closed by the sameswitch. At vthis ignition position'of the throttle' v lever 83. there isa maximum of rheostat resistance in the motor circuit and, therefore.aminlmum of power input to the fuel pump P. Under' these conditions thepump P produces a comparatively small fuel pressure. When the glow plugs40 have reached a fuel igniting tempera-v ture, .and the fuel pressurehas come up to the starting pressure, thev lever 8,3 lis* advanced tothe starte;` position.y This actuates the vswitch 90 to #complete thecircuit to the starting system andthepower plant is started. ,When thecompressors |9'and and vtliegturloine I3 are up to about 15% of theirnormal speed, vsufficient air issupiplied by the compressors toestablish an appreciable differential pressure in the pipes |04 and-|06. This pressure differential is communicated 'to the fuel valveactuating pistons |00 and |01 in the cylinders 98 and 99, and'tends tomove the fuel control needle valves downwardly eff their seats94 and 95.When the throttle controllever 83 is at the starter position on thesector 81, the spring 85 is under suicient vcompression to hold Ltheneedle valve 93l ofthe piston rod 86 rmly closed vbut the compression inthe `spring 82 is at this pointso balanced that as soon as the ow ofairthrough the burner tubes is established to a given value during-thestartin'gcycle-ithe above mentioned l resultantwdifferential pressuresacting 1 on the piston |00' isy Isufficient*to crack;v or slightly openthe needle valve -92 ofstem lill andallowa proper -amountof the'fu'eltoifflowthrough line- 96 -v to the primary fueljjet manifold 13s and'thence vto the spray jets 31jin-the burnerftubes This initiates.operation' ofv thepower plant and the f. power plant is brought upv tothe idling speed.

Upon a further advance of the control leve'r 83 from the starterposition the compressive force of the spring 82 is further relaxed,tending to allow` the primary fuelneedle valve 92 to open further and tofeed a greater quantity of fuel to the burner jets. However, regulatoryforces are immediately and automatically superimposed `upon the fuelcontrol valve motion to meter the fuel allowed to ilow'tothe burner jetsin accordance with thequantity of flow of air through the combustionzone." This'insures a proper and em cient fuel mixture toproducea'nearly constant combustion temperature, thereby protecting the gasturbine from thermal damage. These regulatory forces are applied to theneedle valve stems, ForV example, the primary fuel valve stem 8| isurgedinfa direction to re-close the needle valve 92 by thefriction ofthe increased f ,flow-.offuel'upwardly around the piston |09 andelectrical energy |23 which circuit in turnA con-.k-

lfrom this disclosure because it is not essential to" an understandingof thepresent invention. The

thefforce appliedto the piston |09 through the "pipe |04 tends'to movethe needle valve to an open position. The lforceapplied to the piston maiet-nus opposed totneteppued to the piston |00 andtend'stofreturnitheneedle valve`92 to a closed `position upon theflow offuel through the ylinders; Thisfrce'is caused byy the difieren-f1tialpressureimposedLk y y frictional flowof-fue thrQii'ghQthesmallclear'.

n the piston |09 by the 7 ance space between the piston and the cylinderwall and toward the valve outlet 94. The flow of fuel from the primaryfuel valve is thus a modied combined function of the rates of flow offuel and air to the combustion zone which tends under all conditions tomaintain a proper fuelair ratio for any given power control setting,

'assuming a substantially constant fuel viscosity.

Up to this point in the initial stages of Aoperation of the power plantthe supplemental fuel needle valve stem 86 has remained in its closedposition against the seat 95 under the compressive force of the spring85. When the control lever is still further advanced on the sector 81and approaches the position marked Supplemental Fuel, the spring 85reaches a state of elongation where its compressive force is reduced toa value which permits the supplemental fuel needle metering valve 93 tolift off its seat 95. This allows supplemental fuel to flow through theline 91 and the tubular rotor shaft to the supplemental fuel orifices 49in the apex 48 of the gas turbine rotor. Supplementary fuel is thussprayed into the secondary combustion chamber Il Where it burns in thepresence of the excess air carried in the gas turbine exhaust. Stillfurther advance of the control lever results in further opening of thesupplemental fuel valve 93 to supply an added quantity of fuel to thesecondary combustion zone. The metering of the supplementary fuel issubject to the same automatic regulation as that before described inconnection with the primary metering valve. As a result the total nalquantity of fuel, both primary and supplementary, does not exceed thatrequired for the burning of all of the air leaving the gas turbine. Thisavoids the loss of raw fuel through the propulsive nozzle of thepowerplant.

During the above described forward advancements of the control lever 83the rheostat III is actuated through its associated linkage toprogressively decrease its resistance and thus increase the power inputto the motor M which drives the fuel pump P. Accordingly the fuelpressure delivered to the metering valve mechanism varies as anapproximate function of the demand. The needle valves of the meteringmeans do not in fact appreciably throttle the fuel but rather the fuelpump speed is directly controlled at the fuel pressure source accordingto the fuel quantity requirements and the combustion air back pressure.The needles 92 and 93 regulate or trim the now to the exact quantitiesrequired with only a small throttling action. This conserves electricpower and prevents fuel vapor lock due to frictional overheating.Furthermore, the fuel pressure system makes possible the use of smallfuel lines because the fuel pressure drop in the line is compensated forby the fuel control system. Thus a further controlling factor iscombined with the automatic characteristics of the fuel metering valvemechanism and tends to impart automatic regulatory characteristics tothe unit as a whole.

For example, in the event the control lever 83 is moved forward suddenlyan immediate increase in fuel pressure with a momentary correspondingincrease in ow to the burner results. This momentary increase in flow ofthe fuel takes care of the acceleration and increased primary andsupplementary fuel requirements of the power unit under high poweroutput conditions.

Having thus described my invention and the present preferred embodimentsthereof, I desire to emphasize the fact that many modicaticns 8 may beresorted to in a manner limited only by a just interpretation of thefollowing claims.

Iclaim:

1. A power plant comprising a compressor, a gas turbine driving thecompressor, a primary combustion chamber between the turbine andcompressor, a secondary combustion chamber at the downstream side of theturbine, fuel injection means for the primary combustion chamber. fuelinjection means for the secondary combustion chamber, a source of fuelunder pressure, means responsive to pressure conditions in thecompressor and primary combustion chamber for metering the delivery offuel from said source to the primary combustion chamber, meansresponsive to pressure conditions in the compressor and primarycombustion chamber for metering the delivery of fuel from said source tothe secondary combustion chamber, and a control operable to sequentiallyoperate said metering means so that a given fuel-air ratio is firstestablished in the primary combustion chamber and subsequently a givenfuel-air ratio is established in the secondary combustion chamber.

2. A power plant comprising a compressor, a gas turbine driving thecompressor, a primary combustion chamber between the turbine andcompressor, a secondary combustion chamber at the downstream side of theturbine, fuel injection means for the primary combustion chamber, fuelinjection means for the secondary combustion chamber, a source of fuelunder pressure, means sensitive to fuel ow to the primary chamber and toair pressure conditions in the compressor and primary combustion chamberfor metering the delivery of fuel from said source to the injectionmeans of the primary chamber, means sensitive to fuel flow to thesecondary chamber and to air pressure conditions in the compressor andprimary combustion chamber for metering the delivery of fuel from saidsource to the injection means of the secondary chamber, and a singlemanual control for sequentially conditioning said metering means foroperation.

3. A gas turbine power plant comprising a compressor, a turbine, acombustion chamber between the compressor and turbine, a source of fuel,a pump for pumping fuel under pressure from said source to thecombustion chamber for injection therein, variable speed power means foroperating the pump, metering means between the pump and combustionchamber sensitive to fuel flow pressure and to the rate of air flow fromthe compressor and operable to effect a fine regulation of fuel flow tothe combustion chamber, and means for varying the speed of operation ofthe power means to effect the primary regulation of fuel delivery to thecombustion chamber.

4. A gas turbine power plant comprising a compressor, a turbine, acombustion chamber between the compressor and turbine, a source of fuel,a variable output pump means for pumping the fuel to the combustionchamber, means interposed between the pump means and combustion chambersensitive to fuel flow pressure and to the rate of air flow into thecombustion chamber to effect a fine regulation of the fuel now to thecombustion chamber, and manually operablemeans for varying the speed ofoperation of the pump means to eifect a primary regulation of fueldelivery to the combustion chamber.

5. A gas turbine power plant comprising a compressor, a turbine, acombustion chamber between the compressor and turbine. a source of fuel,a variablefoutput pump for pumping the' speed of operation of the pumpto effect the primary regulation of fuel delivery to the combus tionchamber, and manually operable means for actuating the primary' controlmeans and for biasing said fine regulation means.

6. A gas turbine power plant comprising a ccmpressor, a turbine, acombustion chamber between the compressor and turbine, a source of fuel,a variable output pump for pumping the fuel to the combustion chamber,means interposed be` tween the pump and combustion chamber sensitivetofuel flow pressure and to the rate of air flow into the combustionchamber to effect a fine regulation of the fuel flow to the combustionchamber, a primary control means for varying the speed of operation ofthe pump 'to effect the primary regulation of fuel delivery to thecombustion chamber, and a single manual control for simultaneouslyoperating the primary control means and biasing said ne regulationmeans.

7. A gas turbine power p'ant comprising a compressor, a gas turbine, acombustion chamber between the compressor and turbine, a pump forpumping fuel into the combustion chamber, vari- .abe power means foroperating the pump, fuel metering means interposed between the pump andthe combustion chamber including a fuel metering valve, a pistonassociated with the valve and acted upon by the fuel flowing to thecombustion chamber to urge the valve closed, and a manually operablethrottle control for simultaneously varying the output of said powermeans and the position of the valve.

8. A gas turbine power plant comprising a compressor, a gas turbine, acombustion chamber between the compressor and turbine, a pump forpumping fuel into the combustion chamber, variable power means foroperating the pump, fuel metering means interposed between the pump andthe combustion chamber including a fuel metering valve, a pistonassociated with the valve, means for applying pressure from thecompressor to one side of the piston, means for supplying pressure fromthe combustion chamber to the other side of the piston, the dierentialin said pressures tending to operate the metering valve, and a manuallyoperable control for varying the output of said power means and theposition of the valve.

, ond piston associated with said valve, means for supplying pressurefrom the compressor to one side of the second piston, means forsupplying pressure from the combustion chamber to the other side of thesecond piston, the differential in said pressures tending to operate themetering valve, and a manually operab'e throttle control forsimultaneously varying the output of said power means and the positionof the valve,

10. A gas turbine power plant comprising a compressor, a gas turbine, aprimary combustion chamber between the compressor and turbine, asecondary combustion chamber, a pump for pumping fuel to said chambers,variable power means for driving the pump, a fuel metering meansinterposed between the pump and each of said chambers, each meteringmeans including a fuel metering valve, and a piston associated with thevalve acted upon by the fuel fiowing to the respective chamber to urgethe valve closed, and manual means for sequentially operating saidvalves and for varying the output of said power means. g

11. A gas turbine power plant comprising a compressor, a gas turbine, aprimary combustion chamber between the compressor and turbine, asecondary combustion chamber, a pump for pumping fuel to said chambers,variabe power means for driving thc pump, a fuel metering meansinterposed between the pump and each of said chambers. each meteringmans includingr a fuel rretering valve, a first piston associated withthe valve and acted upon by the fuel flowing to the respectivecombustion chamber to urge the valve closed, a second piston associatedwith the valve, means for supplying pressure from they v compressor t0one side of the second piston, and

means for supplying pressure from the combustion chamber to the otherside of the second piston, the differential in said pressures tending tooperate the valve, and manua'ly operable means lfor simultaneouslyvarying the output of said and the primary chamber, a second fuelmetering valve means interposed between the pump and the supplementalchamber means for dividing tbe fuel flow from the pump into separatestreams for flow through said separate valve means, a single manualcontrol lever. and operative connections between the lever and saidmetering valve means related so that the metering valve means areoperated in sequence upon movement of the lever.

13. A gas turbine power plant comprising a compressor, a gas tvrbine, aprimary combustion chamber between the compressor and turbine, asupplemental combustion chamber at the downstream side of the turbine, apump for pumping fuel to said chambers, a first fuel metering meansinterposed between the pump and the primary chamber, a second fuelmetering means interposed between the pump and the supplemental chamber,a manual control lever, and elastic means connected between the lei-erand said metering means related so that the metering means are operatedin sequence upon movement of the lever.

14. A gas turbine power plant comprising a compressor, a gas turbine, aprimary combustion chamber between the compressor and turbine, asupplemental combustion chamber at the downstreamside of the turbine, apump for pumping fuel to said chambers, a first fuel metering meansinterposed between the pump and the primary chamber, a second fuelmetering means interposed between the pump and the supplemental 11chamber, a manual control lever, and compression springs engaged betweenthe lever and said metering means related so that the metering means areoperated in sequence upon movement of the lever. l

15. A gas turbine power plant comprising a compressor, a gas turbine, aprimary combustion chamber between the compressor and turbine, afsupplemental combustion chamber at the downstream side of the turbine, apump for pumping fuel to said chambers, a first fuel metering meansinterposed between the pump and the primary chamber, a second fuelmetering means interposed between the pump and the supplemental chamber,a manual control lever, elastic operative connections between the leverand said metering means operable to produce sequential operation of themetering means upon movement of the lever, and a calibrated sectorassociated with the lever for indicating the operative condition of thetwo metering means.

16. In a gas reaction propulsive unit, apparatus comprising incombination, a flow system for air and gases including a gas turbine, anozzle communicating with the exhaust of said turbine and adapted toproduce a propulsive jet, primary and secondary combustion chambers, the

` primary combustion chamber including an air and fuel mixing regionhaving a high velocity throat,

`means to introduce combustion gases from said primary combustionchamber into said turbine, means to pass combustion gases from saidturbine into said secondary combustion chamber and the said nozzle, acompressor driven by said turbine, and means to pass compressed air fromsaid compressor to said primary combustion chamber; means to introducefuel to said primary combustion chamber; means to introduce fuel intosaid secondary combustion chamber; a manually settable fuel throttlecontrol; and means responsive to the combined functions of the rate ofnow o! compressed air into said primary combustion chamber measured bythe differential between the pressure in said compressor and thepressure in said throat of the primary combustion chamber and thethrottle control setting to meter the rate of said introduction of saidfuel into the primary and secondary combustion chambers.

17. Apparatus according to claim 16 in which said means to meter fuelincludes a primary metering valve for metering fuel for the primarycombustion chamber .and a secondary metering valve for metering fuel forthe secondary combustion chamber operable successively first to controlthe introduction of fuel into the primary combustion chamber only, andsubsequently to control introduction of fuel into both the primary andsecondary combustion chambers.

NATHAN C. PRICE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS and 242.

